Device for incinerating waste gas

ABSTRACT

A device for incinerating waste gases has a combustion chamber, burner for burning waste gas in the combustion chamber, and a tubular conduit extending substantially vertically from the combustion chamber so that products of combustion of the waste gas in the combustion chamber travel vertically upwardly through the tubular conduit, the tubular conduit being composed of a plurality of tubular elements located one above the other and arranged relative to one another so as to form a gap between each two neighboring tubular elements for introducing air into an interior of the tubular conduit through the gaps.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. application Ser. No.09/961,757, filed Sep. 25, 2001 (with the same title, filed by Ely Y.Zborovsky, Registered Patent Agent No. 28,563), the entire disclosure ofwhich is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to devices for incineration ofwaste gases.

[0003] There is a frequent need in the oil and gas industry to disposeof flammable gases. This is usually necessary because small quantitiesof gas are either not economical to process or are toxic and must beneutralized. The most common means for eliminating these gases is toburn them in the atmosphere using a flare stack. This device typicallyis formed as a tall pole with an open diffusion flame anchored at thetop. The orange color of the flame and the intermittent presence ofblack soot are evidence that the combustion process is not particularlyefficient with this type of apparatus. The efficiency can be furtheradversely affected by the presence of ambient winds. Some parts of adiffusion flame are relatively cool and the residency time of thecombustibles in the flame can be quite short. Under some conditions,certain chemical species may not undergo complete thermal decompositionand oxidation. This can lead to the release of toxic substances, forexample hydrogen sulphide, into the atmosphere. The results areobnoxious odors and an unsightly flame, both of which have become thetargets of environmental groups and government regulatory agencies.

[0004] It is known that efficient burners are used in industrialincinerators. However, the combustion chamber in these devices istypically lined with a glass or ceramic refractory liner in order toprotect the chamber walls from the high temperature corrosive gases.Some methods of minimizing the heat transfer from hot exhaust gases tothe surrounding duct walls for the purpose of minimizing the emittedinfrared radiation from a war ship are proposed in U.S. Pat. No.4,355,507 and Canadian patent no. 1,134,827. These methods employ thewell known phenomenon of film cooling.

[0005] It is believed that improvements in waste gas incineratingdevices are both desirable and achievable via the appropriateapplication of similar film cooling techniques.

SUMMARY OF THE INVENTION

[0006] Accordingly, it is an object of present invention to provide adevice for incinerating waste gases, which avoids the disadvantages ofthe prior art. In keeping with these objects and with others which willbecome apparent hereinafter, one feature of present invention resides,briefly stated, in a device for incinerating waste gases, comprising acombustion chamber; means for burning waste gas in said combustionchamber; and a tubular conduit extending substantially vertically fromsaid 110 combustion chamber so that products of combustion of the wastegas in said combustion chamber travel vertically upwardly through saidtubular conduit, said tubular conduit being composed of a plurality oftubular elements located one above the other and arranged relative toone another so as to form a gap between each two neighboring tubularelements for introducing air into the interior of said tubular conduitthrough said gaps.

[0007] In accordance with another feature of the present invention, thetubular elements have different diameters such that a tubular elementwith a greater diameter is located above a tubular element with asmaller diameter to form the gap therebetween.

[0008] In accordance with another feature of present invention, thetubular elements of the tubular conduit are formed so that the gaps areopen outwardly so that the air can be introduced through the gaps fromoutside inwardly into each of the tubular elements.

[0009] In accordance with still a further feature of present invention,means is provided for the forced supply of air through the gaps betweensaid tubular elements.

[0010] In accordance with still a further feature of present invention,an additional tubular enclosure is arranged around the tubular conduitso that air is supplied first in a space between the tubular conduit andthe tubular enclosure and then travels through the gaps into theinterior of the tubular conduit.

[0011] In accordance with still another feature of present invention,each of the gaps is sub divided in a circumferential direction by aplurality of partitions which serve to connect the tubular elements withone another and also to straighten the flow of air entering the gaps.

[0012] In accordance with still a further feature of the presentinvention, the partitions of one gap are circumferentially offsetrelative to the partitions of the other gap to form offset slotstherebetween.

[0013] The novel features which are considered as characteristic for thepresent invention are set forth in particular in the appended claims.The invention itself, however, both as to its construction and itsmethod of operation, together with additional objects and advantagesthereof, will be best understood from the following description ofspecific embodiments when read in connection with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a view schematically showing a device for incineratingwaste gas;

[0015]FIGS. 2 and 3 are views showing two modifications of the inventivedevice for incinerating waste gas; and

[0016]FIG. 4 is a plan view of the inventive device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A device for incinerating waste gases shown in FIG. 1 has acombustion chamber which is identified as a whole with reference numeral1. It can be provided with a plurality of burners which are identifiedwith reference numeral 2 and can be formed from known commercial burnerswhich are used for burning gases. A number and location of the burners 2in the combustion chamber 1 is selected in accordance with the type andvolume of waste gas to be incinerated and other related parameters.

[0018] The device for incinerating waste gases is further provided witha tubular conduit which is identified as a whole with reference numeral3. The tubular conduit 3 extends vertically upwardly from the combustionchamber 1. It is to be understood that the combustion chamber 1 is openinto the interior of the tubular element 3. For example a grate 4 can bearranged between the combustion chamber 1 and the tubular conduit 3 topermit the products of combustion of the waste gas to flow verticallyupwardly from the combustion chamber 1 into the tubular conduit 3.

[0019] In accordance with the present invention, the tubular conduit iscomposed of a plurality of tubular elements 5. The tubular elements 5are shown as cylindrical tubular elements. However, of course, they canalso have another cross-section, while then only being necessary tocomply with the main requirement to have a peripherally closed wall. Inaccordance with the present invention, the tubular elements 5 havedifferent diameters. In particular the diameters of the tubular elementsincrease vertically upwardly, so that the tubular element with a smallerdiameter is located lower, and the tubular element with the greaterdiameter is located higher, correspondingly. The tubular elements 5 arearranged relative to one another so that a gap 6 is formed between twoneighboring tubular elements. The combustion chamber 1 is provided withan auto ignitor 7 which is known in the art.

[0020] While FIG. 1 shows a general schematic view of the inventivedevice for incinerating waste gases, FIGS. 2 and 3 show furtherdifferent embodiments of the inventive device. FIG. 2 shows the devicefor incinerating waste gases in accordance with the present invention,which is preferably used in a field remote from urban areas. As can beseen from FIG. 2 the gaps 6 between the tubular elements 5 are retainedopen to the outside. During the operation of the device shown in FIG. 2,the waste gas is burned by the burners 2 in the combustion chamber 1 andthe products of combustion flow upwardly into the tubular conduit 3.During upward movement of the products of combustion, air is aspiratedthrough the gaps between the tubular elements 5 as a consequence of thelow static pressure that exists inside the tubular conduit 3. eachtubular element is fitted along its lowermost edge with a peripherallyoriented external tube 5′ that promotes structural rigidity of thetubular element and also provides a well rounded inlet for the airentering gap 6

[0021] The tubular conduit 3 protects the combustion process fromambient winds. It also removes the combustion process from public view.The entrained ambient air both protects the inner walls of the tubularconduit from the hot corrosive gases and also convects away the heatradiated from the hot gases to the inner walls, and thereby it is notnecessary to provide a refractory liner as in known devices. Entrainedambient air also ensures well-ventilated and efficient combustion. Also,the resulting combustion products are diluted by ambient air before theyexit the device. This aspect of the invention, in conjunction with thefact that the gases inside the conduit achieve significant verticalvelocity, results in lower ground-level concentrations of combustionproducts than for an equivalent conventional flare stack. This isimportant from both a regulatory point of view and from the standpointof minimizing odours. The device shown in FIG. 2, because of its openslots 6. of course produces some noise, and therefore, it is notrecommended to be used in urban areas.

[0022] In contrast, the device shown in FIG. 3 is recommended for urbanareas. The device shown in FIG. 3 substantially corresponds to thedevice shown in FIG. 2, but in addition it has means for forced supplyof air which is identified with reference 8. The means for forced supplyof air can be formed for example as a centrifugal air blower.Additionally a tubular enclosure 9 is provided which surrounds thetubular conduit 3 so as to form a peripheral space therebetween.

[0023] During the operation of the device shown in FIG. 3, air isforcedly supplied by the centrifugal blower 8 into a space between thetubular enclosure 9 and the tubular conduit 3, and then air flowsthrough the gaps 6 into the interior of the corresponding tubularelements 5 of the tubular conduit 3, with the results which werepreviously explained herein in connection with the device shown in FIG.2. Since the device is provided with the enclosure 9 it does notgenerate excessive noise and, therefore, can be used in urban areas.

[0024]FIG. 4 shows the structure of the gaps 6 between the tubularelements 5. As can be seen from this drawing, each gap is subdividedinto a plurality of slots which adjoin one another in a peripheraldirection. The subdivision of the gap 6 into slots 10 is performed bypartitions 11. The partitions 11, in addition to the subdivision of thegaps 6 into the slots 10, serve for connection of the two adjoiningtubular elements 5 with one another. They are preferably formed asconnecting ribs. These partitions reduce the adverse effect of crosswinds on the flow entering the gaps 6.

[0025] As can be also seen from FIG. 4, the slots 10 of different gaps 6are offset relative to one another in a peripheral direction. Thisprovides a more efficient distribution of air supply into the interiorof the tubular conduit 3.

[0026] Complete thermal decomposition and oxidation of noxioussubstances require that the combustible be maintained above a thresholdtemperature for a minimum duration. The required temperature andduration depend on the substances being burned. With the presentinvention it is possible to control the temperature history andresidency time of the substances being combusted by an appropriateselection of the size and position of the entraining slots 10 relativeto one another, and the overall heights of the conduit 3.

[0027] It will be understood that each of the elements described above,or two or more together, may also find a useful application in othertypes of constructions differing from the types described above.

[0028] While the invention has been illustrated and described asembodied in device for incinerating waste gas, it is not intended to belimited to the details shown, since various modifications and structuralchanges may be made without departing in any way from the spirit of thepresent invention.

[0029] Without further analysis, the foregoing will so fully reveal thegist of the present invention that others can, by applying currentknowledge, readily adapt it for various applications without omittingfeatures that, from the standpoint of prior art, fairly constituteessential characteristics of the generic or specific aspects of thisinvention.

[0030] What is claimed as new and desired to be protected by LettersPatent is set forth in the appended claims:

1. A device for incinerating waste gas, comprising a combustion chamber;means for burning waste gas in said combustion chamber; and a tubularconduit extending substantially vertically from said combustion chamberso that products of combustion of the waste gas in said combustionchamber travel vertically upwardly into said tubular conduit, saidtubular conduit being composed of a plurality of tubular elementslocated one above the other and arranged relative to one another so asto form a gap between each two neighboring tubular elements forintroducing air into the interior of said tubular conduit through saidgaps.
 2. A device as defined in claim 1, wherein said tubular elementshave different diameters such that a tubular element with a greaterdiameter is located above a tubular element with a smaller diameter toform said gap therebetween.
 3. A device as defined in claim 1, whereinsaid tubular elements have a cross section other than circular.
 4. Adevice as defined 1, wherein said tubular elements of said tubularconduits are formed so that said gaps are open outside so that the airis aspirated through said gaps from outside inwardly into each of saidtubular elements.
 5. A device as defined in claim 1, wherein the number,size and position of said gaps are chosen so that the wall temperatureof the tubular elements does not exceed a specified value.
 6. A deviceas defined in claim 1, wherein the number, size and position of saidgaps are chosen so as to provide the maximize possible dilution of thecombustion products before said products exit said tubular conduit.
 7. Adevice as defined in claim 1, wherein the number, size and position ofsaid gaps are chosen so as to ensure the combustion products exceed aspecified temperature for a specified duration before said products exitsaid tubular conduit.
 8. A device as defined in claim 1; and furthercomprising means for forced supply of air through said gaps between saidtubular elements.
 9. A device as defined in claim 1, wherein anadditional tubular enclosure is arranged around said tubular conduit sothat air is supplied first in a space between said tubular element andsaid tubular enclosure and then travels through said gaps into aninterior of said tubular conduit.
 10. A device as defined in claim 1wherein each of said gaps is subdivided in a circumferential directionby a plurality of partitions which form a plurality of slots and alsoserve for connecting said tubular elements with one another.
 11. Adevice as defined in claim 1, wherein the partitions of one gap arecircumferentially offset relative to the partitions of the other gap.12. A ground flare stack for incinerating waste gases, the stack havinga lower tubular portion and an upper tubular exhaust portion,comprising: (a) a tubular burn chamber located intermediate the lowerand upper portions and having combustion air intakes located below theburn chamber, (b) one or more pairs of waste gas inlet ports and closureports, the inlet and closure port of each pair being located on opposingsides of the burn chamber, (c) a service access port located in thestack at an elevation equal to or below the waste gas inlet ports; (d)one or more primary burner assemblies fitted within the burn chamberbetween the inlet and closure ports, the burner assemblies acceptingwaste gases from the inlet port and discharging waste gases into theburn chamber for mixing with the combustion air for creating exhaustgases; and (e) the tubular exhaust stack having one or more axiallydisplaced tubular exhaust shells, each upwardly adjacent exhaust shellhaving a greater diameter than the preceding exhaust shell, the exhaustshells forming a contiguous bore and being concentrically spaced forforming one or more annular inlets for admitting additional annular airinto the stack for discharge with the exhaust gases.
 13. The groundflare stack as recited in claim 12 wherein the annular inlets admitsufficient additional annular air for improved dispersion of the exhaustgases into the atmosphere.
 14. The ground flare stack as recited inclaim 12 further comprising one or more auxiliary burners fitted withinthe tubular exhaust stack above at least one of the one or more annularinlets, the annular inlets admitting additional annular air as primarycombustion air for the one or more auxiliary burners to the stack. 15.The ground flare stack as recited in claim 13 wherein each axiallydisplaced tubular exhaust shell has a lower edge at the annular inletwhich is fitted with a bell-mouth intake so as to result in an improvedintake of additional annular air.
 16. The ground flare stack as recitedin claim 15 wherein the bell mouth intake comprises a hoop of a circularcross-section.
 17. The ground flare stack as recited in claim 16 whereinthe two or more auxiliary burners are fed waste gas from a header. 18.The ground flare stack as recited in claim 17 wherein hoop is tubularand has a bore so that the hoop's bore forms the header.